1. Field of the Invention
Eastern black nightshade (Solanum ptycanthum) is an economically important weed in much of the midwestern United States. It can cause crop yield reductions by competition, but is more notorious for interfering with harvest and lowering the crop quality. The foliage and berries of eastern black nightshade can foul combines and make harvesting nearly impossible. Moreover, the berries contaminate and stain the crop seeds and initiate mold growth during storage. Several species of weedy nightshades, including the eastern black nightshade, have in the past been generically referred to as "black nightshade" (Solanum nigrum L.). In accordance with a recent taxonomic revision, the eastern black nightshade is now designated as a separate species, Solanum ptycanthum.
This invention relates to a method of controlling eastern black nightshade by means of infection with a fungal pathogen.
2. Description of the Prior Art
The merits for using pathogens to control weeds in annual crops have been discussed previously for various fungal species. Daniel et al., U.S. Pat. No. 3,849,104 teaches the use of an endemic anthracnose fungus, Colletotrichum gloeosporioides forma specialis aeschynomene, to control the northern jointvetch weed in rice fields. A related species, C. malvarum, has been reported by Templeton in U.S. Pat. No. 3,999,973 as a control for prickly sida (Sida spinosa L.) or teaweed, particularly in soybean and cotton fields. C. malvarum is also pathogenic toward other noncultivated species, including velvetleaf. C. coccodes has been well documented as a widely distributed pathogen of potato and tomato, as well as 35 other plant species throughout the world. One isolate of C. coccodes has been studied as a potential mycoherbicide for velvetleaf by Gotlief et al. [Proc. Weed Sci. Soc. Am. 37: 68 (1984)].
Walker [Weed Sci. 29: 505-507 (1981)] discloses the use of Alternaria macrospora as a pathogen against spurred anoda. In Walker, U.S. Pat. No. 4,390,360, A. cassiae is disclosed as an effective biological control agent for sicklepod, showy crotalaria, and coffee senna. Finally, Walker teaches in U.S. Pat. No. 4,419,120 that Fusarium lateritium is useful in controlling prickly sida, velvetleaf, and spurred anoda.